Brake booster questions, Again

I had the hydro booster in my truck replaced, I left the shop, drove home and popped the hood to find the the new (reman) htdrobooster was leaking at the seam where the to parts mate. I took it back and the mechanic tighten the bolts because they were loose. It still continued to leak so he ordered and installed a new booster. Well, after a week I crawled under the dash to find that the booster is leaking into the cab again. Now he wants to put a booster from a 2500 series truck into mine because he said it will be more "heavy duty" I did some research and found that the boosters are different. Mine is rated for 7,200 lbs, the 2500 is rated for 9,500 lbs. I think that I have an issue with him installing the 2500 series unit on my truck. He stated "well, if I put the 2500 in it will stop on a dime". I still don't like it. What is your opinion? Please no lectures about getting the part from another supplier of going somewhere else. The part is Cardone, which happens to be the company that supplies autozone, advance and oreillys with the booster. I am stuck at this shop because that is where the warranty company sent me.